Arterial blood gas interpretation worksheet with answers

Free printable Arterial blood gas interpretation worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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Name: ____________________   Date: ____________

1.Easy

Practice values: Na⁺ 131, K⁺ 4.2, Cl⁻ 95 and HCO₃⁻ 15 mmol/L. Calculate the anion gap AG = Na⁺ − (Cl⁻ + HCO₃⁻), without potassium.

Na⁺ 131 mmol/LK⁺ 4.2 mmol/LCl⁻ 95 mmol/LHCO₃⁻ 15 mmol/L
AG = mmol/L
2.Easy
pH7.357.457.50PaCO₂mmHg354541HCO₃⁻mmol/L222631respiratorymetabolicacidosisalkalosis

A practice arterial blood gas shows pH 7.50, PaCO₂ 41 mmHg (5.5 kPa) and HCO₃⁻ 31 mmol/L. Which primary disorder is it? Click the cell in the grid.

pH 7.50PaCO₂ 41 mmHg (5.5 kPa)HCO₃⁻ 31 mmol/L
  1. 1respiratory acidosis
  2. 2metabolic acidosis
  3. 3respiratory alkalosis
  4. 4metabolic alkalosis
3.Medium

A practice gas shows PaCO₂ 27 mmHg (3.6 kPa). Use the rule that in chronic respiratory alkalosis HCO₃⁻ falls by 5 mmol/L for every 10 mmHg that PaCO₂ is below 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.

PaCO₂ 27 mmHg (3.6 kPa)baseline: 40 mmHg, 24 mmol/L
HCO₃⁻ = mmol/L
4.Medium

A practice gas shows a metabolic acidosis with HCO₃⁻ 18 mmol/L. Use Winter’s formula to find the expected PaCO₂ (the centre of the range) in mmHg.

HCO₃⁻ 18 mmol/L
PaCO₂ = mmHg
5.Hard
pH7.357.457.28PaCO₂mmHg354524HCO₃⁻mmol/L222611appropriate compensationadded respiratory acidosisadded respiratory alkalosis

A practice gas shows a metabolic acidosis: pH 7.28, PaCO₂ 24 mmHg (3.2 kPa), HCO₃⁻ 11 mmol/L. Compare the measured PaCO₂ with Winter’s formula. Click your interpretation.

pH 7.28PaCO₂ 24 mmHg (3.2 kPa)HCO₃⁻ 11 mmol/L
  1. 1appropriate compensation
  2. 2added respiratory acidosis
  3. 3added respiratory alkalosis
6.Hard

Practice values: Na⁺ 141, Cl⁻ 113, HCO₃⁻ 16 mmol/L and albumin 24 g/L. Find the albumin-corrected anion gap AGc = AG + 0.25·(40 − albumin).

Na⁺ 141 mmol/LCl⁻ 113 mmol/LHCO₃⁻ 16 mmol/Lalbumin 24 g/L
AGc = mmol/L

Answer key

  1. 1. AG = 21 mmol/L
  2. 2. metabolic alkalosis
  3. 3. HCO₃⁻ = 17.5 mmol/L
  4. 4. PaCO₂ = 35 mmHg
  5. 5. appropriate compensation
  6. 6. AGc = 16 mmol/L

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